Global Shutter Image Sensor Layout for Storage Node Light Shielding
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Solution Overview
Problem
Global shutter image sensors suffer from high parasitic light sensitivity due to their storage nodes, which are easily affected by light, leading to image distortion and blurring.
Innovation Solution
An image sensor design incorporating a substrate with a global shutter component, a ground doped region, and a light-shielding layer, where the light-shielding layer is electrically connected to the ground doped region and includes a first layer covering the storage node and a second layer surrounding the global shutter component, effectively reducing light incidence on the storage node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If global shutter component with storage node is used, then image distortion is reduced, but parasitic light sensitivity increases
Solution Approach 1:
A light-shielding layer is introduced as an intermediary element between the storage node and incident light. This layer includes a first light-shielding layer covering the storage node from above and a second light-shielding layer surrounding the global shutter component, effectively blocking light paths while preserving the global shutter's image quality benefits
Solution Approach 2:
The light-shielding structure extends into the vertical dimension with the first light-shielding layer positioned above the storage node and the second light-shielding layer forming a surrounding structure. This three-dimensional light-shielding approach blocks light from multiple directions (top and sides) without affecting the horizontal pixel array functionality
2Manufacturing precision
If storage node is added for global shutter, then image distortion is decreased, but light sensitivity increases
Solution Approach 1:
The light-shielding layer serves as a protective intermediary that allows the storage node to fulfill its image accuracy function while being shielded from harmful light exposure. The first light-shielding layer specifically covers the storage node, and the second light-shielding layer surrounds the entire global shutter component
Solution Approach 2:
The light-shielding structure is locally applied where needed: the first light-shielding layer is positioned specifically over the storage node region, while the second light-shielding layer surrounds the global shutter component. This localized approach reduces light sensitivity without interfering with other functional regions of the image sensor
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The light-shielding layer significantly reduces parasitic light sensitivity by blocking light from above and stray light from the sides, minimizing image distortion and blurring.
Implementation Method 1
the light-shielding layer on the pixel array region blocks the light from the above, and the light-shielding layer on the border region blocks the stray light from the side
Data Source
AI summary
An image sensor includes a substrate, a global shutter component, a ground doped region, and a light-shielding layer. The substrate at least has a pixel array region and a border region adjacent to each other. The global shutter component is located on the pixel array region, and the global shutter component includes a storage node. The ground doped region is located on the border region. The light-shielding layer is located on the pixel array region and the border region and is electrically connected to the ground doped region. The light-shielding layer includes a first light-shielding layer and a second light-shielding layer. The first light-shielding layer is located on the pixel array region and covers the storage node, and the second light-shielding layer is located on the border region and surrounds the global shutter component. A manufacturing method of an image sensor is also provided.